“We’re going to be upfront and honest about everything,” he said, adding that any social media advert run by the anti-abortion group would carry its branding and would not be paid for by foreign donations.

He acknowledged concerns about external influence in the referendum campaign. “In terms of the overseas funding and overseas influence, it’s very hard to stop . . . It’s reasonably unregulated,” he said.

A referendum to repeal the Eighth Amendment to the Constitution, which provides a right to life to the unborn, will be held later this year.

Billboard campaign

Save the 8th launched on Monday a national billboard campaign featuring the testimony of two healthcare workers.

Caren Ní hAllacháin worked as an agency nurse in the Royal Hospital for Women, in Sydney, Australia, during the early 1990s, where she witnessed a termination at 22 weeks, after which the child lived for a short period.

“To this day it haunts me. I know for a fact it haunts other nurses,” she said. “The Eighth Amendment protects the mother and protects the baby.”

Noel Patrún, who worked in a UK hospital theatre that provided terminations, said the Eighth Amendment was a “good law”, adding that mental health difficulties among women following terminations was a “silent epidemic in Britain”.

There was a contradiction, he said, where “doctors and obstetricians are helping people get pregnant in one room” and providing terminations in the next theatre.